| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
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| 3. |
- Miao, Yuyang, et al.
(författare)
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Bidirectional Association between Major Depressive Disorder and Gastroesophageal Reflux Disease : Mendelian Randomization Study
- 2022
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Ingår i: Genes. - : MDPI. - 2073-4425. ; 13:11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Observational research has found a bidirectional relationship between major depressive disorder and gastroesophageal reflux disease; however, the causal association of this relationship is undetermined. Aims: A bidirectional Mendelian randomization study was performed to explore the causal relationships between major depressive disorder and gastroesophageal reflux disease. Methods: For the instrumental variables of major depressive disorder and gastroesophageal reflux disease, 31 and 24 single-nucleotide polymorphisms without linkage disequilibrium (r(2) <= 0.001) were selected from relevant genome-wide association studies, respectively, at the genome-wide significance level (p <= 5 x 10(-8)). We sorted summary-level genetic data for major depressive disorder, gastroesophageal reflux disease, gastroesophageal reflux disease without esophagitis, and reflux esophagitis from meta-analysis study of genome-wide association studies involving 173,005 individuals (59,851 cases and 113,154 non-cases), 385,276 individuals (80,265 cases and 305,011 non-cases), 463,010 individuals (4360 cases and 458,650 non-cases), and 383,916 individuals (12,567 cases and 371,349 non-cases), respectively. Results: Genetic liability to major depressive disorder was positively associated with gastroesophageal reflux disease and its subtypes. Per one-unit increase in log-transformed odds ratio of major depressive disorder, the odds ratio was 1.31 (95% confidence interval [CI], 1.19-1.43; p = 1.64 x 10(-8)) for gastroesophageal reflux disease, 1.51 (95% CI, 1.15-1.98; p = 0.003) for gastroesophageal reflux disease without esophagitis, and 1.21 (95% CI, 1.05-1.40; p = 0.010) for reflux esophagitis. Reverse-direction analysis suggested that genetic liability to gastroesophageal reflux disease was causally related to increasing risk of major depressive disorder. Per one-unit increase in log-transformed odds ratio of gastroesophageal reflux disease, the odds ratio of major depressive disorder was 1.28 (95% confidence interval, 1.11-1.47; p = 1.0 x 10(-3)). Conclusions: This Mendelian randomization study suggests a bidirectional causal relationship between major depressive disorder and gastroesophageal reflux disease.
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| 4. |
- Kohse-Höinghaus, Katharina, et al.
(författare)
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Chemistry diagnostics for monitoring
- 2023
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Ingår i: Combustion Chemistry and the Carbon Neutral Future : What will the Next 25 Years of Research Require? - What will the Next 25 Years of Research Require?. - 9780323992138 ; , s. 417-501
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Bokkapitel (refereegranskat)abstract
- Chemically sensitive diagnostics are indispensable to unravel reactive processes in combustion and beyond, to understand their development in time and space and to monitor the reaction progress under the conditions of interest. A multitude of techniques is available that may provide species composition together with other process-controlling variables as a function of the reaction environment. Analytical tools have been developed that range from one-of-a-kind large-facility instrumentation to robust sensors for use in technical systems and in the field. In this chapter, needs and developments for the near and midterm future are addressed combining individual contributions from selected perspectives and intertwining thoughts and ideas from different fields and expertise. Major advances can be expected from combinations of instrumentation and digital processes, with beneficial uses for a multitude of processes in carbon-reduced and carbon-neutral environments.
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| 5. |
- Li, Yuyang, et al.
(författare)
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A General Carboxylate-Assisted Approach to Boost the ORR Performance of ZIF-Derived Fe/N/C Catalysts for Proton Exchange Membrane Fuel Cells
- 2021
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 31
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Tidskriftsartikel (refereegranskat)abstract
- An Fe/N/C catalyst derived from the pyrolysis of metal-organic frameworks, for example, a zeolitic-imidazolate-framework-8 (ZIF-8), has been regarded as one of the most promising non-precious metal catalysts toward oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). However, its ORR mass activity is still much inferior to that of Pt, partly because of the lack of general and efficient synthetic strategies. Herein, a general carboxylate-assisted strategy that dramatically enhances the ORR mass activity of ZIF-derived Fe/N/C catalysts is reported. The carboxylate is found to promote the formation of Fe/N/C catalysts with denser accessible active sites and entangled carbon nanotubes, as well as a higher mesoporosity. These structural advantages make the carboxylate-assisted Fe/N/C catalysts show a 2-10 fold higher ORR mass activity than the common carboxylate-free one in various cases. When applied in H-2-O-2 PEMFCs, the active acetate-assisted Fe/N/C catalyst generates a peak power density of 1.33 W cm(-2), a new record of peak power density for a H-2-O-2 PEMFC with non-Pt ORR catalysts.
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| 6. |
- Li, Yuyang, et al.
(författare)
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A Library of Potential Nanoparticle Contrast Agents for X-Ray Fluorescence Tomography Bioimaging
- 2018
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Ingår i: Contrast Media & Molecular Imaging. - : WILEY-HINDAWI. - 1555-4309 .- 1555-4317.
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Tidskriftsartikel (refereegranskat)abstract
- Nanoparticles (NPs) have been used as contrast agents for several bioimaging modalities. X-ray fluorescence (XRF) tomography can provide sensitive and quantitative 3D detection of NPs. With spectrally matched NPs as contrast agents, we demonstrated earlier in a laboratory system that XRF tomography could achieve high-spatial-resolution tumor imaging in mice. Here, we present the synthesis, characterization, and evaluation of a library of NPs containing Y, Zr, Nb, Rh, and Ru that have spectrally matched K-shell absorption for the laboratory scale X-ray source. The K-shell emissions of these NPs are spectrally well separated from the X-ray probe and the Compton background, making them suitable for the lab-scale XRF tomography system. Their potential as XRF contrast agents is demonstrated successfully in a small-animal equivalent phantom, confirming the simulation results. The diversity in the NP composition provides a flexible platform for a better design and biological optimization of XRF tomography nanoprobes.
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| 7. |
- Li, Yuyang, et al.
(författare)
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Changes in Water Chemistry Associated with Rainstorm Events Increase Carbon Emissions from the Inflowing River Mouth of a Major Drinking Water Reservoir
- 2022
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 56:22, s. 16494-16505
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Tidskriftsartikel (refereegranskat)abstract
- Large reservoirs are hotspots for carbon emissions, and the continued input and decomposition of terrestrial dissolved organic matter (DOM) from upstream catchments is an important source of carbon emissions. Rainstorm events can cause a surge in DOM input; however, periodic sampling often fails to fully capture the impact of these discrete rainstorm events on carbon emissions. We conducted a set of frequent observations prior to and following a rainstorm event in a major reservoir Lake Qiandao (China; 580 km(2)) from June to July 2021 to investigate how rainstorms alter water chemistry and CO2 and CH4 emissions. We found that the mean CO2 efflux (FCO2) (13.2 +/- 9.3 mmol m(-)(2) d(-1)) and CH4 efflux (FCH4) (0.12 +/- 0.02 mmol m(-2) d(-1)) in the postrainstorm campaign were significantly higher than those in the prerainstorm campaign (-3.8 +/- 3.0 and +0.06 +/- 0.02 mmol m(-)(2) d(-)(1), respectively). FCO2 and FCH4 increased with increasing nitrogen and phosphorus levels, elevated DOM absorption (a(350)), specific UV absorbance SUVA(254), and terrestrial humic-like fluorescence. Furthermore, FCO2 and FCH4 decreased with increasing chlorophyll-a (Chl-a), dissolved oxygen (DO), and pH. A five-day laboratory anoxic bioincubation experiment further revealed a depletion of terrestrial-DOM concurrent with increased CO2 and CH4 production. We conclude that rainstorms boost the emission of CO2 and CH4 fueled by the surge and decomposition of fresh terrestrially derived biolabile DOM in this and likely many other reservoir's major inflowing river mouths.
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| 8. |
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| 9. |
- Li, Yuyang
(författare)
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Synthesis and Characterization of Nanoprobes for X-Ray Fluorescence Computed Tomography (XFCT) Bio-imaging
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- X-ray fluorescence computed tomography (XFCT) is an emerging biomedical imaging technique. The KTH-XFCT laboratory system offers a characteristic 24 keV emission line, and high spatial resolution (200 ?m) images. XFCT as a newly emerging modality also requires the exploration and development of suitable contrast agents. Nanomaterials have been widely used as contrast agents in many popular imaging modalities like MRI, PET, and CT. They have several advantages including long blood circulation time, high ratio of surface area to volume, and enhanced image contrast. However, the use of nanomaterials as contrast agents is limited by their biocompatibility and toxicity, which are determined by the physicochemical properties including size, morphology, surface chemistry. Therefore, the study on the synthesis and characterization of nanomaterials is an indispensable step. In this thesis, a group of elements (Y, Zr, Nb, Ru, Rh) are selected based on the X-ray K?-absorption energy, matching with the 24 keV emission line of KTH-XFCT source. Y, Zr, Nb, Ru and Rh based nanoparticles are synthesized by hydrothermal and polyol method, identified as the ceramic and metallic groups. XRF performance is demonstrated by the XFCT system. Metallic Ru and Rh nanoparticles are further selected to study the synthesis conditions and in vitro toxicity for their smaller TEM and hydrodynamic size. Surface properties are investigated to show the isoelectric point and polymer coating on the metallic nanoparticles. Morphological different Rh nanoparticles are obtained by introducing different additives during the synthesis, indicating the different cytotoxicity performance attributed to different morphologies. Silica coating is further performed on the surface of metallic and metallic nanoparticles to improve their biocompatibility. The in vitro toxicity assessment are performed on the murine macrophages and human ovarian cancer cell lines. X-ray fluorescence performance is evaluated for each nanoparticles by using soft-tissue equivalent holder and in situ small-animal imaging experiments. The results indicates the spatial resolution and detection sensitivity of the concentration of the metallic nanoparticles. In this work, we demonstrate the potential of a group selected nanomaterials as XFCT contrast agents for the first time, especially, investigate the synthesis, surface properties, in vitro toxicity as well as detection sensitivity of the metallic nanoparticles.
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| 10. |
- Li, Yuyang, et al.
(författare)
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Synthesis and Cytotoxicity Studies on Ru and Rh Nanoparticles as Potential X-Ray Fluorescence Computed Tomography (XFCT) Contrast Agents
- 2020
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 10:2
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Tidskriftsartikel (refereegranskat)abstract
- X-Ray fluorescence computed tomography (XFCT) is an emerging biomedical imaging technique, which demands the development of new contrast agents. Ruthenium (Ru) and rhodium (Rh) have spectrally attractive K ff edge energies, qualifying them as new XFCT bio-imaging probes. Metallic Ru and Rh nanoparticles are synthesized by polyol method, in the presence of a stabilizer. The effect of several reaction parameters, including reaction temperature time, precursor and stabilizer concentration, and stabilizer molecular weight, on the size of particles, were studied. Resultant materials were characterized in detail using XRD, TEM, FT-IR, DLS-zeta potential and TGA techniques. Ru particles in the size range of 1-3 nm, and Rh particles of 6-9 nm were obtained. At physiological pH, both material systems showed agglomeration into larger assemblies ranging from 12-104 nm for Ru and 25-50 nm for Rh. Cytotoxicity of the nanoparticles (NPs) was evaluated on macrophages and ovarian cancer cells, showing minimal toxicity in doses up to 50 mu g/mL. XFCT performance was evaluated on a small-animal-sized phantom model, demonstrating the possibility of quantitative evaluation of the measured dose with an expected linear response. This work provides a detailed route for the synthesis, size control and characterization of two materials systems as viable contrast agents for XFCT bio-imaging.
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